Adolescent substance use is a major public health concern in Europe. The SUNT project (short for Developing the Substance Use Normalization Theory) is the first of its kind to develop the “substance use Normalization Theory” which is a novel theoretical framework to explain adolescent substance use in contemporary society. Building on the Normalization Thesis, the project aims to put in place a novel theoretical framework that uniquely relies on Social Control Theory and other traditional risk factor theories and places them in a framework that explicitly addresses the link between the social context of youth and substance use risk factors. Furthermore, the project rigorously tests the substance use Normalization Theory by using different datasets and novel methodologies. The theoretical framework and the empirical analyses aim to help researchers reach a better understanding of contemporary patterns of adolescent substance use, which in turn, promises to generate important information for policy makers across the EU and member states.To reach the aim of the research, the project mainly relies on novel data analysis of secondary data gathered as part of the Health Behaviour in School aged Children study (HBSC). HBSC data are based on nationally representative samples of youth from 43 countries. In addition, we have conducted a time trend analysis using Israeli HBSC data collected over a period of 15 years and we have conducted a systematic review of the extant normalization literature was conducted. The first set of analysis that the team has conducted showed that according to expectations based on low cannabis prevalence rates in all countries studied, no evidence of normalization was found for recent cannabis use. Also in line with the Normalization Theory, results show that for substance use that reaches above 40% in at least some of the countries studied (drunkenness, alcohol and cigarette use), adolescents who reported use are less likely to report social and behavioral risk factors in high prevalence countries than in low prevalence countries. However, support for the Normalization Theory was only partial in that results show that in models where evidence for normalization was found, there are risk factors that predict substance use to an equal degree regardless of country level prevalence rates. These results have been published in Social Science and Medicine. The lack of evidence for normalization of cannabis use led the research team to examine the Normalization Theory in relation to different levels of cannabis use (e.g. experimental versus regular cannabis use) as opposed to using the gross last month measure. This led to the exploration of models of cannabis use normalization with different multinomial HLM modeling techniques. Results show that as expected based on the Normalization Theory, evidence of normalization was found for cannabis experimentation but not for regular cannabis use. As such, the SUNT project is the first to demonstrate the importance of distinguishing between different levels of cannabis use when assessing the Normalization Theory, both for theory and policy development and in terms of paving the way for more nuanced Drug Normalization studies. These results has been published in Journal of Studies on Alcohol and Drugs.We are also the first to conduct a literature review of the extant research on the normalization theory. By synthesizing the literature we found that the most commonly assessed dimension of drug use normalization was “experimentation”. In addition to the original dimensions, the review identified the following new normalization dimensions in the literature: (1) breakdown of demographic boundaries and other risk factors in relation to drug use; (2) de-normalization; (3) drug use as a means to achieve normal goals; and (4) two broad forms of micro-politics associated with managing the stigma of illicit drug use: assimilative and transformational normalization. The SUNT project is the first to synthesize the extant literature and to make practical suggestions for future directions in this evolving field of research. Specifically, we suggest that quasi-experimental designs that are currently being made feasible by swift changes in cannabis policy provide researchers with new and improved opportunities to examine normalization processes.Impact: The studies conducted have important theoretical and social impacts. First of all, the project is the first to develop the Normalization Theory and successfully test it and prove its empirical validity in a dataset of 31 European and American countries and overtime with time trend data. This is a meaningful step forward in the development of social science drug use research and theory. In terms of policy implications, the published studies lay out in detail the implication of the study findings for policy. In particular, it is noted that results of the studies suggest that selective prevention efforts may be particularly useful in low prevalence countries where screening based on risk factors may usefully identify adolescents at most risk for developing drug use problems. This approach may be less useful in high prevalence countries where screening based on risk factors is less likely to satisfactorily identify those at risk for developing drug use problems.By summarizing the normalization literature in a systematic review we have also pointed out that the normalization theory is particularly suited to research the implication of current policy changes (such as cannabis legalization). Future research ought to examine whether legalization leads to media exposure that re-frames cannabis in a way that leads to cultural and social accommodation and in turn increased use. In our review we found that very few normalization studies have focused on the policy dimension. We suggest that this area is especially suitable for normalization research and that focusing on changes in drug policies may lead to a better understanding of normalization processes as well as a better understanding for contemporary societal and individual influences of substance use.